CAREER: Morphodynamics of Mixed-Energy Tidal Inlets: Sediment Bypassing Processes

University Of Florida, Gainesville FL

Investigators

Abstract

Human populations are strongly concentrated along the coasts, and, consequently, coastal ecosystems are some of the most impacted and altered environments worldwide. Due to increasing sea levels, storm intensities, and human activities, there is an imperative need to better understand coastal dynamics of flow, sediment transport, and changes in the shape of the coastline and the bottom (morphodynamics). In the past, there have been some attempts to better understand and predict coastline evolution of sandy beach areas. However, the morphodynamic response of estuary mouths and adjacent beaches to external forces (e.g. waves, tides, river outflows) has received less attention. Nonetheless, inlets play a key role in the wide variety of ecological, economic, and social services associated with estuaries, adjacent beaches, and back-barrier lagoons. The main research goal in this project is to improve the understanding of the processes that lead to sediment movement from the up-drift to down-drift sides of inlets (bypassing). The investigator will analyze the main processes driving the shoreward movement of sand bars over the ebb-tidal delta, how the interactions between tidal and littoral currents affect the alongshore and cross-shore sediment transport, and the morphodynamic effects of infragravity waves. The project will also integrate hands-on experiences to enhance the teaching of coastal morphodynamics. Lessons and educational material will be produced targeting secondary science teachers, and graduate students will be trained and engaged in applying a constructivist approach to learning at the high school level. Morphodynamics of mixed-energy inlets are still not fully understood due to the complex feedbacks between the highly temporally and spatially varying morphology, waves, tides, river flow, and mixing conditions. One of the key processes in inlet morphodynamics is sediment bypassing. It affects the sediment budget of the inlet and the sand supply to the inner bay, ebb-tidal delta, and adjacent beaches. The most accepted conceptual models of inlet bypassing could benefit from two improvements. First, swash bars over the ebb-tidal delta may not be transported onshore due, primarily, to wave swash. Rather, they should be primarily transported by surfzone currents. Additionally, littoral currents contribute to inlet bypassing not only in wave-dominated inlets, but also in mixed-energy inlets. How tidal and littoral currents interact and affect sediment transport along and across the inlet deserves additional studies. Infragravity waves might also play a primary role in inlet sediment transport processes. This project will combine in situ and remote field observations and numerical modeling at Matanzas Inlet (FL) to analyze, test and integrate these processes to improve our knowledge of sediment transport processes in mixed-energy inlets. Findings generated from this study will help us better understand the dynamics of these coastal systems and will contribute to the improvement of coastal management tools and procedures. Research and education will be fostered through the involvement of the graduate students in the PI's research group in the educational activities. In collaboration with the Center for Precollegiate Education and Training at the University of Florida, the team will develop and implement four 5E lessons geared towards high-school students and secondary science teachers. This collaboration will provide the graduate students with the opportunity to be trained in the application of the 5E instructional method at the high-school level. A curricular module for a Summer Institute course directed towards secondary science teachers will also be developed as part of this project. The direct interaction with teachers through this collaborative initiative will promote the inclusion of key concepts of coastal morphodynamics (beach, estuaries, and inlets) into the K-12 science curriculum.